Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, monolithic windows, and/or the like.
Conventional low-E coatings are disclosed, for example and without limitation, in U.S. Pat. Nos. 6,576,349, 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345, the disclosures of which are hereby incorporated herein by reference.
Certain low-E coating utilize at least one transparent dielectric layer of titanium oxide (e.g., TiO2), which has a high refractive index (n), for antireflection and/or coloration purposes. See for example U.S. Pat. Nos. 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345. Although high refractive index dielectric materials such as TiO2 are known and used in low-E coatings, these materials are typically not heat stable after tempering process of about 650 C for 8 minutes, due to film crystallization (or change in crystallinity) in as-deposited or post-tempering state, which may in turn induce thermal or lattice stress on adjacent layers in the film stack. Such stress can further cause change in physical or material properties of the stack and hence impact on the Ag layer, which results in deteriorated low E stack performance.
Example embodiments of this invention solve these problems by providing a high index layer for use in low-E coatings that both has a high refractive index (n) and is substantially stable upon heat treatment (HT).
“Heat treatment” (HT) and like terms such as “heat treating” and “heat treated”, such as thermal tempering, heat strengthening, and/or heat bending, as used herein means heat treating the glass substrate and coating thereon at temperature of at least 580 degrees C. for at least 5 minutes. An example heat treatment is heat treating at temperature of about 600-650 degrees C. for at least 8 minutes.
In example embodiments of this invention, a high index layer for use in low-E coatings is provided that both has a high refractive index (n) and is substantially stable upon heat treatment (HT). A coated article includes a low emissivity (low-E) coating having at least one infrared (IR) reflecting layer of a material such as silver, gold, or the like, and at least one high refractive index layer of or including NbBi. The high index layer (e.g., NbBiOx) is designed and deposited so as to be amorphous in the low-E coating, so as to better withstand optional heat treatment (HT) such as thermal tempering. The high index layer may be a transparent dielectric high index layer in preferred embodiments, which is provided for antireflection purposes and/or color adjustment purposes, in addition to having thermal stability. In certain example embodiments, the low-E coating may be used in applications such as monolithic or insulating glass (IG) window unit, vehicle windows, of the like.
In an example embodiment of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first transparent dielectric layer on the glass substrate; an infrared (IR) reflecting layer comprising silver on the glass substrate, located over at least the first transparent dielectric layer; a second transparent dielectric layer on the glass substrate, located over at least the IR reflecting layer; and wherein at least one of the first and second transparent dielectric layers is amorphous and comprises an oxide of Nb and Bi.
In an example embodiment of this invention, there is provided a method of making a coated article including a coating supported by a glass substrate, the method comprising: sputter depositing a first transparent dielectric layer on the glass substrate; sputter-depositing an infrared (IR) reflecting layer comprising silver on the glass substrate, located over at least the first transparent dielectric layer; sputter-depositing a second transparent dielectric layer on the glass substrate, located over at least the IR reflecting layer; and wherein at least one of the first and second transparent dielectric layers is sputter-deposited so as to be amorphous or substantially amorphous, and comprise an oxide of Nb and Bi.
In an example embodiment of this invention, there is provided a method of making a coated article including a layer supported by a glass substrate, the method comprising: having a glass substrate; sputter-depositing an amorphous, or substantially amorphous, layer comprising an oxide of Nb and Bi on (directly or indirectly) the glass substrate. The layer may be sputter-deposited in an oxygen depleted atmosphere (an atmosphere including less oxygen gas than needed to form a fully stoichiometric oxide layer) so that a difference in cationic radii for Nb and Bi causes lattice disorder leading to amorphous or substantially amorphous structure of the layer.